Economic burden of type 2 diabetes in Iran: A cost‐of‐illness study

Abstract Background and Aims Type 2 diabetes mellitus (T2DM) is a prevalent public health problem worldwide, and the economic burden of the disease poses one of the main challenges for health systems in low‐ and middle‐income countries. This study aimed to estimate the economic burden of T2DM in Iran, in 2018. Methods This was a cost‐of‐illness study. Three hundred and seventy‐five patients with T2DM who were referred to Imam Reza and Sina's educational and therapeutic centers and Asad Abadi clinic in Tabriz, Iran, in 2018 were included. A researcher‐constructed checklist was used for data collection. Data were analyzed using EXCEL and SPSS software version 22. Results Total economic burden of diabetes was estimated at 152,443,862,480.3 (purchasing power parity [PPP], Current International $) (approximately 7.69% of GDP, PPP, Current International $). The mean total direct and indirect costs were 11,278.68 (PPP) (62.35% of mean total cost) and 6808.88 (PPP, Current International $) (37.64% of the total cost), respectively. The mean total direct medical cost and the direct nonmedical cost were 10,819.43 (PPP, Current International $) (59.81% of mean total cost) and 459.24 (PPP, Current International $) (2.53% of mean total cost) per patient, respectively. Besides, the mean direct medical cost was 6.18 times the total per capita expenditure on health, and the total direct medical cost was 8.9% times the total expenditure on health. Conclusion Diabetes imposes a substantial economic burden on patients, health systems, and the whole economy. Besides, since the cost of the disease in patients treated with insulin and those with diabetes complications is significantly higher, the reinforcement of self‐care measures and focusing on modifying lifestyle (dietary modification and physical activity) in patients with T2DM can significantly reduce the costs of the disease.


| Study design
This prevalence-based cost of illness study was conducted from the societal perspective using bottom-up approach costing.

| Study setting and population
The statistical population included all patients with type 2 diabetes in East Azerbaijan province referring to Imam Reza and Sina's educational and therapeutic centers and Asad Abadi clinic in Tabriz, Iran, in 2018. The population of East Azerbaijan province is estimated at 4 million, and the rate of diabetes incidence is 10%. So, the population of patients with diabetes is estimated at 40,000, and based on the Morgan table, 375 patients with T2DM were selected.
Hence, based on the calculated population size and incidence rate, the estimated population is estimated at 40,000. Due to the inaccessibility to all of the statistical population in our study, the convenience sampling method was used consecutively.
A researcher-made checklist was used for data collection. The checklist design process was as follows: interview with endocrinologists (n = 7), interview with researchers who had conducted at least one cost of illness study (n = 3), interview with professors in Health Economics (n = 2), interview with T2DM patients (n = 15), and the review of records of inpatients and outpatients of T2DM patients.
The checklist consists of demographic variables (age, gender, supplementary insurance status, and the type of basic insurance), duration of the disease, treatment type, and questions about diabetes-related costs. The questionnaires were completed during a 20-min face-to-face interview by one of the research team.

| Cost classification and definition
In this study, the economic burden of diabetes was estimated by calculating direct medical costs, direct nonmedical costs, and indirect costs for a year. Direct medical costs were expenditures related to medical services and drugs associated with diagnosis and treatment performed in hospitals and clinics. Direct nonmedical costs included commuting costs and costs associated with accommodations and extra nutrition for patients with diabetes during the period of treatment. Indirect costs were defined as days of lost productivity for both patients and their family members caused by outpatient visits and hospitalization due to diabetes. Moreover, data related to outpatient costs, direct nonmedical costs, and missed workdays were collected once every 2 months for a year using the checklist.

| Cost estimation
In the present study, data related to the hospitalization part of direct medical costs were extracted from patients' records, and outpatient parts of direct medical costs and direct nonmedical costs were obtained via an interview with patients and their families, respectively.
Indirect cost was estimated based on the Human Capital Approach via GDP per capita (2018), lost productivity due to missed workdays, and premature death due to diabetes. First, to estimate the cost of missed workdays per patient, we calculated the annual average number of missed workdays of the patients and their families due to diabetes and then multiplied it by the GDP per capita; in this way, we estimated the cost of missed workdays per patient. To calculate the cost of premature death due to disease, the average duration of premature death was multiplied by GDP per capita (Formulas (1) and (2)): Formula (1)

| Data analysis
Data analysis was performed using EXCEL and SPSS version 22.
Descriptive statistics (mean and SD) were used for cost estimates.
Spearman correlation coefficient (CC) was used to examine the association between cost items and age, duration of the disease, the number of hospitalization, and Mann-Whitney for the association between mean costs and gender, informal payment, basic insurance coverage, supplemental insurance coverage, and habitation status.
Kruskal-Wallis for the association between mean costs and age, Insurance type, treatment type, and cause of hospitalization. The tests were carried out at a 5% significance level, and a p-value ≤ 0.05 was considered as significant.    Table 2). The contribution of basic insurance, patient, subsidy, supplementary insurance, and hospital discount in the reimbursement of hospitalization costs was 82.54%, 7.25%, 6.95%, 2%, and 1.22%, respectively. Table 4 reports the proportion of cost components from the total cost of type 2 diabetes. Total direct medical costs to the T2DM patients (all inpatients and outpatients) in the study were 10,819.43 (PPP, Current International $) per patient, making up 59.99% of the mean total costs. For outpatients, the mean total direct medical costs, the mean total nonmedical direct costs, and the mean total indirect costs accounted for 58.19%, 2.23%, and 39.57% of mean total costs, respectively. For inpatients, the mean total direct medical costs, the mean total nonmedical direct costs, and the mean total indirect costs accounted for 63.27%, 3.17%, and 33.54% of total mean costs.   where i = 0.05 and N = 10.

| Ethics approval and consent to participate
Discounted total mortality costs = Future value/discount factors = insurance, and these patients are deprived of receiving essential services due to their inability to pay for medical costs. Therefore, it is necessary to identify these patients and take the necessary supportive measures to improve their access to essential healthcare services and financial protection of these patients against the catastrophic costs incurred by the disease by the government, health insurance organizations, charities, and other related institutions.
The cost of the disease was more likely to be higher among those under Iranian health insurance coverage than those under social security insurance. This difference may be due to two reasons: first, the Social Security Administration may have been more successful in managing the costs of diabetes, and second, Iranian health insurance may have provided more services to these patients. However, without sufficient information about the quantity and quality of services provided to patients covered by these two insurance organizations, as well as information about the quality of liferelated to healthcare and clinical outcomes of these two groups, a definite judgment is not possible, and needs further investigation.

| LIMITATIONS
This study has some limitations. The cost of decreased productivity at work due to disability and its complications and loss of income due to job changes caused by diabetes and its complications have not been estimated.

CONFLICTS OF INTEREST STATEMENT
The authors declare no conflicts of interest.

DATA AVAILABILITY STATEMENT
The datasets used and/or analyzed during this study are available from the corresponding author upon reasonable request.

TRANSPARENCY STATEMENT
The lead author Farzad Najafipour affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.